Field of the Invention
The present invention relates to an image forming apparatus that operates in a normal mode and a power saving mode, a control method therefor, and a storage medium.
Description of the Related Art
There is conventionally known an image forming apparatus which operates, to reduce power consumption, in a plurality of power modes, for example, a normal mode of supplying power to all components and a power saving mode of inhibiting power from being supplied to at least a part or all of the components (Japanese Patent Publication (Kokai) No. 2009-223866, for example). The image forming apparatus switches the power mode to the power saving mode if no operation is performed in a certain period of time in the normal mode and switches the power mode to the normal mode if some operation is performed in the power saving mode. The image forming apparatus includes a main central processing unit (CPU), a sub CPU, an engine controller, and an operation display unit.
When the image forming apparatus including components such as the main CPU, the sub CPU, the engine controller, and the operation display unit switches the power mode from the power saving mode to the normal mode, the image forming apparatus performs return processing (FIGS. 7 and 8) of supplying power to each component. The processing of FIG. 7 is performed by the main CPU, the sub CPU, and the engine controller, and the processing of FIG. 8 is performed by the sub CPU.
In FIGS. 7 and 8, first, the main CPU performs start-up processing (steps S701-S703). Specifically, when power is supplied to the main CPU (step S701), the main CPU to which the power is supplied transmits binary data of the sub CPU to the sub CPU and releases a reset state of the sub CPU (step S702), which allows the sub CPU to start start-up processing based on the binary data. Then, the main CPU performs communication preparation processing to communicate with the sub CPU (step S703).
When the reset state of the sub CPU is released, the sub CPU performs start-up processing (steps S711-S713 and S801-803). Specifically, the sub CPU starts a kernel which is a core of an operating system (OS) of the sub CPU (steps S711 and S801), sequentially starts a plurality of device drivers for driving a plurality of devices to be started when the power mode of the image forming apparatus is switched from the power saving mode to the normal mode from, for example, a device driver corresponding to a device arranged around the sub CPU (steps S712 and S802), and establishes virtual communication with the main CPU and the engine controller (steps S713 and S803). Thereafter, the main CPU and the sub CPU communicate with each other by using a predetermined application, and the sub CPU receives information required to communicate with the engine controller, the information being related to devices controlled by the engine controller, for example, a printer and a scanner (hereinafter referred to as “various kinds of device information”) from the main CPU (steps S704, S714, and S804).
The engine controller performs start-up processing independently of the main CPU and the sub CPU (step S721). The start-up processing of the engine controller is completed in a short period of time, so that the engine controller waits until the communication of the main CPU and the sub CPU is completed after the start-up processing is completed (step S722).
Subsequently, the sub CPU communicates with the engine controller, transfers various kinds of device information to the engine controller, acquires status information of the engine controller, and determines whether or not a job can be performed (steps S715, S723, and S805). The main CPU waits until the communication of the sub CPU and the engine controller is completed after the communication with the sub CPU is completed (step S705). When the sub CPU determines that a job can be performed, the sub CPU notifies the main CPU that a job can be performed; the main CPU performs control so that power is supplied to the operation display unit; and the main CPU, the sub CPU, and the engine controller wait until a job is inputted (steps S706, S716, S724, and S806), followed by terminating the program.
However, as described above, the engine controller communicates with the sub CPU after the communication of the main CPU and the sub CPU is completed, so that the engine controller has to wait until the engine controller communicates with the sub CPU after having completed the start-up processing, thereby preventing the power mode of the image forming apparatus from being switched in a short period of time, which provides a problem that it is difficult to quickly switch the power mode of the image forming apparatus from the power saving mode to the normal mode.